As well known to those skilled in the art, an automated warehouse is a building designed to allow a user to keep and manage large stocks of merchandise by taking goods into and out of the warehouse using a stacker. Such an automated warehouse conventionally has a storage rack used for keeping desired goods thereon, with a variety of accessory systems, such as a stacker and a conveyor belt system. Within such a storage rack, the stacker, for example, a stacker crane is used for moving the goods into or out of a warehouse so as to store or deliver the goods. Such a stacker is laid on the storage rack so as to be movable along the rack. Within such automated warehouses, the operation of the stackers and accessory systems is automatically controlled by a computer system.
It is necessary to build such warehouses while accomplishing a desired stable storage of large stocks of goods, a desired improvement in storage efficiency of goods and a stable support for the accessory systems. The automated warehouses are thus typically built in the form of high-story buildings with storage racks having a dual-directional stacker moving structure, wherein a plurality of storage cells are continuously and regularly arranged along two parallel lines in each story of a building while facing each other in the two lines. The storage cells in each line are arranged one after another.
Examples of conventional storage racks having such a dual-directional stacker moving structure are 4-post type storage racks as shown in FIGS. 1a to 1d and 3-post type storage racks as shown in FIGS. 2a to 2d.
Each of the above-mentioned two types of storage racks is referred to the number of posts in each set of posts arranged along a width direction of a rack structure. In the following description, such a set of posts arranged along a width direction of a rack structure will be simply referred to "cross post set." When each cross post set in a storage rack comprises two inside posts, positioned at the central portion, in addition to two outside posts, the rack is so-called "4-post type storage rack" since the number of posts in each cross post set is four (two inside posts+two outside posts). On the other hand, when each cross post set in a storage rack comprises one inside post in addition to two outside posts, the rack is so-called "3-post type storage rack" since the number of posts in each cross post set is three (one inside posts+two outside posts).
As shown in FIGS. 1a to 2d, each of the conventional 4-post and 3-post type storage racks comprises a plurality of posts 1, which are regularly arranged along four longitudinal parallel lines (in the case of 4-post type storage rack) or along three longitudinal parallel lines (in the case of 3-post type storage rack) with regular intervals being defined between the posts 1. Such posts 1 support the vertical load in a storage rack. A plurality of load arms 2 are horizontally and firmly held on the posts 1 at a predetermined height and are used for holding goods thereon. All the posts 1 within each storage rack are connected and integrated together into a single structure by a plurality of lattices 3, horizontal beams 4, horizontal braces 5 and vertical braces 6, and so the rack accomplishes desired horizontal and vertical strength capable of allowing the rack to be free from distortion or buckling.
In such a conventional storage rack, one or two inside posts 1 in addition to two outside posts 2 constitute each cross post set. In the three or four posts 1 of each cross post set, the one or two inside posts 1 form holders for the vertical braces 6 as shown in FIGS. 1d and 2d in addition to partially supporting the vertical load applied to the rack. The above vertical braces 6 are important members necessarily provided in a rack to reinforce the horizontal strength of the rack and to prevent any distortion of the rack structure, and so the vertical brace holding function of the inside post(s) 1 in a conventional rack is very important as follows.
That is, in a storage rack having a dual-directional stacker moving structure, it is inevitable for the vertical braces 6 to be held on the vertical surface(s) of one or two inside posts 1 as shown in FIGS. 1d and 2d since the area around the vertical surface(s) of the inside post(s) 1 or the interfacial area between the two lines of storage cells is free from a forking operational boundary of a stacker crane during a process of taking goods into or out of the storage cells. Therefore, such a conventional storage rack having a dual-directional stacker moving structure has to be fabricated with the inside posts 1.
Due to the structure of holding the vertical braces 6 on the inside posts 1, the conventional 4-post or 3-post type storage racks are problematic as follows.
That is, the inside posts 1 increase the production cost in addition to waste of time and labor while producing the storage racks. This finally reduces productivity and workability while building an automated warehouse having such a storage rack.
The inside posts 1 regrettably form dead areas on the storage racks, thus finally reducing the utility of space in automated warehouses.
It is thus necessary to provide a storage rack for automated warehouses, designed to be free from such inside posts without being ill-affected in its structural strength while having a dual-directional stacker moving structure.